Liquid extracting apparatus and method

ABSTRACT

Apparatus and method, for extracting liquid from a traveling porous web such as a paper machine felt, direct a jet of gas at a surface of the web at an angle to the surface of the web inclined oppositely to the direction of travel, the angle and force of the jet being such that the jet penetrates the web and is reflected back into a collecting chamber, carrying liquid and dirt with it. A wall member is arranged to engage the surface of the web between the chamber and the jet mouth to form a seal to insure the desired web penetration by the jet.

Waite States atent 1191 Baker [111 3,841,910 1 Get. 15, 1974 1 LlQUlDEXTRACTlNG APPARATUS AND METHOD [75] inventor: Donald Brooks Baker,Foxboro,

Mass.

[73] Assignee: Bird Machine Company, llnc., South Walpole, Mass.

22 Flledi Mar. 12,1973

21 Appl.No.:339,972

Related US. Application Data [63] Continuation of Ser. Nos. 27,714,April 13, 1970, abandoned, and Ser. No. 266,124, Junc 26, 1972,

Field of Search;..l34/15, 21, 37; 162/199, 274,-

2,082,411 6/1937 Merril 15/306 A 2,482,781 9/1949 Knowlton et all.15/308 X 2,515,223 7/1950 Hollick 15/306 A X 2,760,410 8/1956 Gillis34/160 X 2,861,354 11/1958 Hultgreen 34/160 X 3,045,273 7/1962 Bruno15/306 A 3,191,210 6/1965 Fischer 15/307 3,495,932 2/1970 Tuma 34/16 X3,546,733 8/1968 Johnson 15/308 3,574,261 9/1971 Bailey 34/23 PrimaryExaminer-Morris O. Wolk Assistant Examiner Arnozo Turk Attorney, Agent,or Firm-Edgar H. Kent 5 7 ABSTRACT Apparatus and method, for extractingliquid from a traveling porous web such as a paper machine felt, directa jet of gas at a surface of the web at an angle to the surface of theweb inclined oppositely to the direction of travel, the angle and forceof the jet being such 345 that the jet penetrates the web and isreflected back into a collecting chamber, carrying liquid and dirt withReferences Clled it. A wall member is arranged to engage the surface ofUNITED STATES PATENTS the web between the chamber and the jet mouth to1,375,663 4 1921 Ainsworth 34 155 ux a seal to insure the desired WebPenetration by 1,501,179 7/1924 Peacock etal. 134/15 x thelet 2,022,59311/1935 Fuykers l5/345 UX 12 Claims 3 Drawing Figures 1 1 1 22 I 2: 2.-l I 1 a 1 I i 1 I l 1 I I lia --.11 I;

LIQUID EXTRACTING APPARATUS AND METHOD This application is acontinuation of my applications Ser. No. 27,714, filed Apr. 13, 1970 andSer. No. 266,124, filed June 26, 1972, both now abandoned.

This invention relates to apparatus and method for extracting liquidfrom traveling porous webs, particularly to such apparatus and methodwhich are useful for conditioning paper machine felts.

A primary object of the invention is to provide such apparatus andmethod which utilize a stream of gas under pressure to eject from theweb contained water and with it dirt more effectively than hasheretofore been possible. Further objects are to provide such apparatuswhich is not expensive to construct or to operate as compared withexisting equipment, which will operate effectively at high speeds oftravel of the web, and which is particularly useful for conditioning thefelts of paper-making machines; and to provide a method which utilizessuch apparatus.

It has been discovered that water (and dirt with it) can be effectivelyremoved from a wet porous traveling web by an apparatus and methodwherein a jet of gas under pressure is directed into one face of the webat a backward angle to the direction of travel of the web and theweb-penetrating portion of the jet is reflected back at an oppositeangle from adjacent the opposite face of the web to and out said oneface thereof into a collecting chamber, the chamber being preferablyunder a vacuum. In order that the jet may operate ef fectively in thismanner, there is provided between the jet and the chamber a wall with anedge engaging the felt continuously across the web and against which theweb is sufficiently tensioned to form therewith a seal, the sealpreventing short-circuiting of the jet to the chamber and providingaccess of the jet to the chamber only by penetration of and reflectancefrom within the web.

Preferred apparatus of the invention includes, opposite a face of theweb being treated, a trough-like, moisture collecting chamber extendingtransversely across the web and having front and rear walls with edgesarranged to engage the said face of the web. The rearward one of thesewalls in the direction of travel of the web comprises or is adjacent toa chamber connected to a source of gas (normally air or steam) underpressure and having a nozzle outlet extending across the web. The nozzleis arranged to discharge the jet into the web at a backward angle to thedirection of travel of the web and rearwardly of the web-engaging edgeof the rear wall of the chamber, the pressure and angle being such thatthe jet penetrates the web and is refiected back outward at an oppositeangle into the collecting chamber, carrying the liquid with it as aspray or stream. The collecting chamber is preferably under vacuum whichmay be of the order of about 2 to inches Hg. However, the jet canoperate, although not as effectively, with the collecting chamber atatmospheric pressure. The rearward wall of the chamber engages the webbetween the jet outlet and chamber with sufficient force to provide therequisite seal between jet and chamber mentioned above.

A support for the opposite face of the web may or may not be provided.If the web being treated is relatively thin and highly porous animpervious support opposite the described equipment may be needed toinsure adequate reflectance of the jetbut with thick,

dense webs such as paper machine felts adequate reflectance canordinarily be obtained from within the body of the web without such asupport. When the web is traveling at high speeds as in the case of thefelts of high speed paper machines, a rotary support opposite the jetand chamber may be advantageous to assist, by centrifugal force, theremoval of liquid into the chamber.

Optimum jet thickness and pressure are variables depending on suchfactors as nature: and porosity of the material being treated, itsthickness and the extent of liquid removal desired. In general it hasbeen found that the jet should be between about 0.002 to 0.007 incheswide, a width of about 0.004 to 0.005 inch being preferred when the gasis compressed air, a lesser width impairing effectiveness in most caseswhile greater width does not usually materially improve performancewhile increasing compression requirements. Within limits and with othervariables fixed it has been found that free liquid removal increases.approximately proportionally to increase of pressure of the jet. Forexample, the extent of water removal from a felt with apparatus asdescribed above having a 0.005 inch wide slit forming an air jet, wasincreased from about 40 percent at 10 p.s.i. (gage), to 65-70 percent at20 p.s.i. to 85 percent at 30 p.s.i., to about 90 percent at 40 p.s.i.,other conditions remaining the same. Similar results were obtained usingsteam as the gas but with lower percentages removal at each p.s.i.level. Since these lower percentages of removal roughly correspond tothe lower density of steam as compared with air, results indicate thatjet density as well as pressure and speed is an important factor, whichshould be kept in mind when correlating results obtained with air toother gaseous media.

The angularity of the jet should be such that its angle of reflectancefrom within the web lies substantially entirely within the confines ofthe collecting chamber. In part, the degree of angularity will depend onthe distance between the adjacent edges of the jet and this chamber,which is preferably as small as possible consistent with the provisionof sealing engagement of the web with the edge of the rear wall of thechamber between the chamber and the jet to prevent shortcircuiting ofany substantial part of the jet over the material being treated into thechamber. With this limitation in mind, the most effective angle is afunction of various factors such as the thickness of the web beingtreated, its porosity, and the speed of its movement past the jet. Theacute angle to the surface of the web should not exceed about nor beless than about 25, 70-75 being preferred.

One particularly useful application of the apparatus and methodaccording to the invention is in the socalled conditioning" of felts ofpulp and paperforming machines. In such practice, the felts, whichtransport the wet sheet to and through the press rolls, are relied uponto remove by absorption much of the water from the sheet. To keep thefelts absorbent, they are treated by felt conditioners after a certainamount of travel or on a continuous-basis to remove the water that hasbeen absorbed and with it fibres and dirt which the felt picks up fromits contact with the fibrous web and which interfere with operability ofthe felt. Felt conditioners have conventionally been vacuum boxes withslotted covers which engage the sheetcontacting face of the felt to suckthe water and foreign matter from it. In some cases these boxes areoscillated.

My apparatus and method, used for felt conditioning and working on thesheet engaging face of the felt, have important advantages overconditioning with these prior devices. With proper control over thevariables as indicated in the foregoing, they can be made to extractmore water and to remove more fibre and dirt. The entire width of thefelt can be treated at each cycle whereas oscillating vacuum boxes treatonly part of the felt at each cycle. The treatment may be uniform acrossthe felt, or it may be made different in different zones as may bedesirable by compartmenting the jet supply passage to correspond to suchzones and varying the gas pressure as desired between compartments.Treatment by my apparatus and method desirably fluffs the sheetcontacting surface of the felt rather than matting it as vacuum boxestend to do, and makes that surface dried. Yet equipment cost andoperating cost are at least comparable with, if not lower than, theseprior devices, The apparatus and method are fully effective at the highspeeds at which paper machine felts are operated.

Similar advantages may be realized when my apparatus and method areutilized for extracting liquid from porous webs other than felts, suchas pile or other fabrics after bleaching, washing or other treatment.

The invention will be further described in connection with theaccompanying drawings which show several preferred forms of theapparatus and of the practice of the method. In the drawings:

FIG. 1 is a cross-section view of such apparatus for use in, and forapplying the method to, felt conditioning, the cross-section being takenon line 11 of FIG. 2 looking in the direction of the arrows;

FIG. 2 is a top plan view of the apparatus shown in FIG. 1, centrallybroken away;

FIG. 3 is a section view similar to FIG. 1 showing a modification of theapparatus according to FIGS. 1 and 2.

Referring to FIGS. 1 and 2, the apparatus therein shown comprises amanifold which is of greater length than the width of the felt F and ismounted adjacent its ends in clamps I2 opposite the working face of thefelt (i.e., the face that contacts the paper on the machine). Clamps 12have upper and lower clamping members 14 and 16 and are held together bybolts 18 which extend rotatably through lugs at the sides of member 14and are received in threaded sockets 20 at opposite sides of member 16.Member 16 is provided at its base with laterally projecting slotted feet22 through which extend bolts 24 fastening the apparatus to a suitablebase B which may be a part of the paper machine frame or a separate baseas convenient.

Provided manifold 10 is under suction to remove the extracted liquidtherefrom as is preferred, the apparatus is not dependent on gravity andmay be mounted beneath the felt or above it or at one side or the otherof a vertical or angular run. In the drawings it is assumed that theapparatus is mounted below a substantially horizontal run of the felthaving its'working face the lower one. Clamps l2 rotatably embracemanifold 10 so that when the bolts 18 are loose; manifold 10 may berotated therein about its axis for position adjustment purposes.

Manifold 10 is preferably provided with suitable coni nections (one ormore, two shown, one at each end) to a source of suction (not shown)capable of maintaining a desired vacuum in the manifold, connections 26extending through end closures 28 of the manifold. Secured to the outerface of manifold 10 between the manifold and the felt is a pressuremanifold 30, which may conveniently be formed as shown of two angleirons welded together and has suitable connections 32 (one or more, twoshown, one at each end) to a source of gas under pressure (not shown)capable of maintaining the desired gas pressure in manifold 30.

Secured to the outer surface of manifold Ml by bolts 34 is a bracket arm36 extending the full width of the felt and having an outwardlyextending portion generally parallel to and spaced from one side ofmanifold 30. Secured to arm 36 by bolts 38 and overlying its outer endis a shoe 40 which defines the leading edge of a slot 42, the oppositeedge of which is defined by a second shoe or bar 4 4 secured by bolts 46to the adjacent side of manifold 30. Slot 42 forms the mouth of acollecting chamber between shoe 44), bar 4 1, arm 36 and manifold 30from which the liquid collected therein flows through a slot $8 in thewall of manifold 10 into the manifold. As indicated on the drawing, shoe40 is formed, preferably, of plastic over which the felt readily slips,such as high density polypropylene.

Bar 44 is beveled on both its forward and rearward faces to taper itsouter end to a narrow edge 50 which defines the leading edge of apressure jet nozzle, the opposite edge of which is formed by a bar 52which is fastened to the outer side of manifold 3f) by bolts 54. Theforward edge of bar 52 is beveled to provide, with the contiguousbeveled end of bar 1%, the nozzle outlet for directing the gas into thefelt at the desired backward angle to the direction of travel of thefelt. Preferably, the forward edge of bar 52 is serrated so that itforms with bar 44 a series of spaced slots 56 (FIG. 2) rather than acontinuous slit, as I have found that the jet produced by such slots isas effective as one that is continuous, requires less pressure and alsoeffectively reduces the noise level. For ease in fabrication, bar 52 maybe formed in sections which are butted at their ends. Gas from manifold30 flows through a series of holes 58 in the manifold wall into a spacebelow bar 52 and thence out the nozzle as indicated by the arrows inFIG. I.

As shown in FIG. 1 the outer surfaces of shoe 40 and bar 52 are smoothand in line with each other and with the edge 50 of bar 44 so that thefelt contacts and rides smoothly on these surfaces and edge. Also, itwill be seen that suction in slot 42 pulls the felt inwardly as itpasses thereover which has a beneficial effect in opening up the workingface of the felt on the suction side and closing the opposite face andalso in insuring sealing engagement of edge 50 with the felt between thejet and the chamber to which slot 42. is the inlet. If suction is notapplied to slot 42, to obtain a similar sealing engagement of the feltwith edge 50 the web should be tensioned against that edge throughoutits width. Escape of the gas entering the felt from its outer surface orby short-circuiting directly into slot 42 is thus inhib thereof (FIG.2), slidable in ways 62 mounted on manifold and extending through endwalls 64 of the structure mounted on manifold 10 into the opposite endsof slot 42. Bars 60 till the space between shoe 40, arm 36 and bar 44 toconfine the suction to the space between their ends.

It will be appreciated that the usual equipment for wetting the felt,normally on the working face, preceding the conditioner, though notshown herein, will normally be provided.

In the modification of FIG. 3 the web W being treated is supported onits back side by a roll R rotating in the direction of the arrow. Such asupport is desirable where the web W is more porous than the usual densepaper machine felts and so porous as to permit enough of the jet toescape from its outer surface if unsupported to impair the desiredejection action by the jet into slot 42. A roll is desirable as asupport because the wrap of the web about the roll opens its exposedface facilitating extraction. It should be appreciated, however, thatthe modified apparatus of FIG. 3 may be also applied to unsupportedfelts or other webs as in FIG. 1.

The modification of FIG. 3 adds a suction slot 70 which follows slot 42and the jet nozzle in the direction of travel of the web for removingresidual moisture passing the jet. To provide slot 70, bracket arm 36with shoe 40, manifold 30 with bar 44 and slot 48 have been movedlaterally of the axis of manifold 10, to the left as viewed in FIGS. Iand 3. A rearward extension 72 on bar 52 defines the leading edge ofslot 70, the opposite edge of which is defined by a shoe 74 mounted bybolts 76 on bracket arm 78 attached to the rear surface of manifold 10by bolts 80. Slot 70 opens into a collecting chamber formed betweenextension 72, shoe 74, manifold 30 and arm 78 which in turn opens intomanifold it) through slot 82 in its wall. The apparatus is otherwise thesame as in the FIGS. I and 2 embodiment.

Separate manifolds in place of the single manifold 10 may of course beprovided for slots 42 and 70 and this will necessarily be done if slot42 is not to be placed under suction. Provision for applying suction tothe web following its treatment by the jet is more important if suctionis not applied to slot 42 which makes the jet less effective, and insuch case the ensuing suction may be applied by a conventional Uhle boxwhich follows the jet applying equipment in the direction of travel ofthe web.

' rous web comprising the steps of:

directing into the web at one face thereof a jet of gas under pressureat one side of a wall, said jet and wall extending across the web andsaid jet being directed into the web at an angle to the plane of the weband opposite to the direction of web travel;

causing the jet to be reflected back from adjacent the opposite web faceto and out said one web face at an opposite angle and at the oppositeside of said wall, carrying extracted liquid therewith;

tensioning said web against the edge of said wall to form a sealpreventing lateral flow of said jet between said wall edge and the web;and

collecting the liquid discharged by said jet in a chamber at theopposite side of said wall from said jet.

2. A method according to claim it wherein said wall forms one side of anozzle for said jet and of said chamber.

3. A method according to claim ll wherein said jet has a width in thedirection of travel of the web of the order of 0.004 to 0.005 inch.

4. A method according to claim I wherein said jet is formed of aplurality of separate gas streams spaced longitudinally of said jet.

5. A method according to claim 1 which includes the further step ofapplying suction to said chamber.

6. A method according to claim 5 wherein said suction produces a vacuumof the order of from 2 to 10 inches Hg.

7. A method according to claim 1 wherein said jet is directed into saidweb at an acute angle to the plane of the web between about 25 and 85.

8. A method according to claim 7 wherein said angle is between about 70and 75.

9. A method according to claim 1 wherein the pressure of said gas jet isat least 10 p.s.i. gage.

10. A method according to claim 9 wherein said pressure is at least 30p.s.i. gage.

11. A method according to claim. I wherein the other face of the web issupported opposite said jet and chamber.

I UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 910Dated October 15, 1974 Inventr(s) DnnaId Brooks Baker It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Co1.'3 line 19, change "dried" to -drier.

Signed and sea1ed this 10th day of December 1974.

(SEAL) Atrest:

McCOY M. GIBSON JR. Attesting Officer c. MARSHALL DANN Commissioner ofPatents FORM DO-O50 (10-69) I UBCOMMJJC 008764 60 I u 5 covr'nuugn'r"mama flmce 000- m a".

1. A METHOD FOR EXTRACTING LIQUID FROM A TRAVELING POROUS WEB COMPRISINGTHE STEPS OF: DIRECTING INTO THE WEB AT ONE FACE THEREOF A JET OFF GASUNDER PRESSURE AT ONE SIDE OF A WALL, SAID JET AND WALL EXTENDING ACROSSTHE WEB AND SAID JET BEING DIRECTED INTO THE WEB AT AN ANGLE TO THEPLANE OF THE WEB AND OPPOSITE TO THE DIRECTION OF WEB TRAVEL; CAUSINGTHE JET TO BE REFLECTED BACK FROM ADJACENT THE OPPOSITE WEB FACE TO ANDOUT SAID ONE WEB FACE AT AN OPPOSITE ANGLE AND AT THE OPPOSITE SIDE OFSAID WALL, CARRYING EXTRACTED LIQUID THEREWITH; TENSIONING SAID WEBAGAINST THE EDGES OF SAID WALL TO FORM A SEAL PREVENTING LATERAL FLOW OFSAID JET BETWEEN SAID WALL EDGE AND THE WEB; AND
 2. A method accordingto claim 1 wherein said wall forms one side of a nozzle for said jet andof said chamber.
 3. A method according to claim 1 wherein said jet has awidth in the direction of travel of the web of the order of 0.004 to0.005 inch.
 4. A method according to claim 1 wherein said jet is formedof a plurality of separate gas streams spaced longitudinally of saidjet.
 5. A method according to claim 1 which includes the further step ofapplying suction to said chamber.
 6. A method according to claim 5wherein said suction produces a vacuum of the order of from 2 to 10inches Hg.
 7. A method according to claim 1 wherein said jet is directedinto said web at an acute angle to the plane of the web between about25* and 85*.
 8. A method according to claim 7 wherein said angle isbetween about 70* and 75*.
 9. A method according to claim 1 wherein thepressure of said gas jet is at least 10 p.s.i. gage.
 10. A methodaccording to claim 9 wherein said pressure is at least 30 p.s.i. gage.11. A method according to claim 1 whereIn the other face of the web issupported opposite said jet and chamber.
 12. A method according to claim11 wherein said other face of the web is supported on an imperviousrotating surface.